The present invention is directed to binders useful in the production of wadding such as is used in the manufacture of decorative, upholstered panels which are to be heat sealed to other substrates using dielectric bonding techniques. The binders of the invention have particular applicability in bonding panel boards to upholstered fabric in the construction of automotive door panels.
In a typical automotive door panel construction, a backcoated woven fabric or a vinyl coated knit is sealed to a nonwoven plumper fabric or wadding which has been spray bonded on each side with a latex binder. The other surface of the wadding is bonded to a rigid polymer coated fiberboard or paperboard sidewall door paneling in a rapid, one step dielectric sealing operation.
When vinyl coated fabrics are employed, the dielectric sealing process causes the vinyl fabric to become thermoplastic and contribute to the bonding of the pad; however, when polyester, nylon or rayon fabrics are employed, they lack this thermoplastic quality and place greater demands on the dielectic sealing properties of the binder composition.
The binders useful in these applications must therefore possess a variety of properties. The wet latex must be stable at the storage and application pH levels of 9 to 10 and all components of the binder composition must be compatible. The binder composition must adhere to a wide variety of surfaces at room temperature and under elevated temperatures; and must be able to withstand increasing voltage levels without arcing or burning during the dielectric sealing process.
Currently employed binders comprise combinations of polyvinyl chloride homopolymers and copolymers thereof with various vinyl or acrylate esters and/or plasticized polyvinyl chloride copolymers and homopolymers optionally blended with crosslinking and non-crosslinking acrylate ester copolymers. The use of higher amounts of the acrylate ester copolymers is becoming more common as the acrylic content provides better adhesion to the polyester, nylon and rayon fabrics which are rapidly replacing fabric backed vinyl.
It is in object of the present invention to provide a wadding binder composition capable of high adhesion and strength at ambient and elevated temperatures and suitable for use on synthetics and natural fabrics as well as vinyl coated fabrics.